The present invention relates to a frame converter which continuously outputs a plurality of image signals in a synchronized state while switching the respective asynchronous image signals.
A device called a video switcher which switches image signals from a plurality of cameras and the like and outputs the signals as one image signal is known. In switching such image signals, the input image signals from the cameras are often asynchronous with each other. The disturbance of synchronous signals in the output image signals is inconvenient.
In this case, all the input image signals are synchronized in advance by using a camera having a TBC (Time Base Corrector) function. Otherwise, asynchronous-isochronous conversion must be performed for each input by using a frame converting device having a frame memory. A camera having the TBC function is expensive, and therefore it is difficult to use the camera in a low-price system.
Further, in the frame converting device, the number of frame memories is the same as that of input image signals. While a image signal is stored into one of the frame memories, reading from another frame memory is performed. In the frame converting device having this construction, the number of frame memories must be the same as that of input image signals. This increases the price of the device.